View Full Version : Noisy AC Tubing
06-17-2006, 12:06 AM
Central AC system was originally a Lennox. Ten years ago the condenser unit failed and was replaced with a Dukane. That one failed last week and was replaced with a Carrier. Works okay but I just noticed that the coolant tubing is making a bubbling noise while the compressor is running. This would be inside, ahead of the connection to the expansion valve. In the past, it was more of a slight "hiss", like water running, which I assume was the sound of the refrigerent moving. Could there be air in the line? It's going to be 90 degrees again tomorrow, please don't tell me it's going to fail this weekend!
06-17-2006, 08:32 AM
The noise you hear is called refrigerant "flash", it's the liquid in the line bubbling off a little bit before it gets to the evaporator. This is normal, and as long as the unit is cooling fine and doesn't freeze up, don't worry about it.
Some coils make this noise more than others, sometimes you can't tell why. Don't worry about it.
06-17-2006, 09:03 AM
Well, it failed. The condenser fan is running, but it doesn't sound like the compresser is. The air isn't being cooled, that's for sure. The after-hours tech for the installer wouldn't listen to me, and insisted that it just couldn't be broken already.
[Edited by theshadow on 06-17-2006 at 11:57 AM]
06-17-2006, 09:15 AM
Changing a major part of an AC will introduce moisture and non condensables.
Therefore, it is best that the AC unit is checked for leaks, evacuated, moisture removed, and properly charged (using superheat, subcooling or weight).
If you have done all those, and you still have the noise - then I would ignore it.
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